3MBIO2_BURDEOSPUGA_PlantArea_PANAY by zyd https://padlet.com/zydpugasci/burdeospuga Creators: Russel Joy Burdeos & Zyd Puga en-us 2021-05-18 11:35:55 UTC 2025-11-15 02:34:20 UTC hello@padlet.com https://padlet-uploads.storage.googleapis.com/1206143028/1203dc4c5d0b7dfd550e09c109bc8446/2743545_middle.png Seed Bank russeljoyburdeossci https://padlet.com/zydpugasci/burdeospuga/wish/1549554599 To conserve and improve the genetic diversity of numerous plant species, several institutions all over the world are taking a collective action through seed banks. These are essentially gene banks of crops which serves as biodiversity databases (Peres, 2016) and as a preventive measure in case of natural disasters.

In the Philippines, the Cordillera Ecological Center also known as PINE TREE established 4 seed banking sites in the Cordillera region in support of the global seed banking movement. Indigenous rice varieties, endemic sweet potato varieties, and beans are being grown in the seed banks (Eurasia Review, 2020). Likewise, seed banks were also set up in several communities in South Cotabato under the project, "Dynamic Conservation and Sustainable Use of Agro-Biodiversity in Traditional Agro-Ecosystems in the Philippines”.
]]> 2021-05-22 01:37:29 UTC https://padlet.com/zydpugasci/burdeospuga/wish/1549554599 Monocot Embryogenesis russeljoyburdeossci https://padlet.com/zydpugasci/burdeospuga/wish/1549556254 Embryogenesis in plants is the process where an embryo is formed and develops, and where axial and radial patterning observed in mature plants are established. As seen in the figure below and, we can see the different stages of development in both monocot and dicot plants. The first step of embryogenesis occurs with the zygote's first cell division, which is asymmetrically creating a smaller apical cell and a larger basal cell. It is at this stage, the Zygotic stage, that the apical-basal axial development pattern is established and observed. The apical part divides to become the embryo while the basal cell divides horizontally along its axis to form a 6-9 cell filament called the suspensor cell which connects the developing embryo to the endosperm. The hypophysis, which is a cell closest to the basal cell and is the only cell derived from the basal cell, contributes to the embryo and further develops into the columella of the root. After the division stage of the zygote into apical and basal cells, the developing embryo undergoes four stages of development.

Four stages of development: 
Globular stage: occurs after the apical cell undergoes several mitotic divisions to create an 8-celled embryo or octant embryo, and then continues to divide to form more globular and further divide to form a fan or triangular-shaped embryo. Radial patterning is first established and continues to develop at this stage, creating the ring layers of structures found in the stems and roots. The outermost cells, the protoderm, give rise to the epidermis. The layer of cells next to the protoderm will give rise to the ground tissue meristem and would eventually form the endodermis and the cortex. Furthermore, the central layer of cells, called the procambium elongates to become the vascular tissues and the pericycle of the root. Heart stage: occurs through rapid cell division on each side of the embryo. Shoot apical meristem (SAM) is formed from the central outgrowths and outgrowths on each side will give rise to the cotyledons. It is at this stage that the bilateral symmetry in the embryo is established, as well as at this stage, regions of apical-basal axial patterning are more clear. The apical region gives rise to the cotyledons and SAM; the central region gives rise to the hypocotyl, root, and the majority of the root meristem; and lastly the hypophysis gives rise to the root meristem. Torpedo stage: occurs due to cell elongation throughout the embryo and the continuous growth in the cotyledon. Maturation stage: where the embryo and the seed start to lose water and enters dormancy and eventually seed germination.

It is noteworthy to mention that in dicot plants, double fertilization occurs before embryonic development begins.



]]> 2021-05-22 01:38:52 UTC https://padlet.com/zydpugasci/burdeospuga/wish/1549556254 Seed Germination russeljoyburdeossci https://padlet.com/zydpugasci/burdeospuga/wish/1549556439 Germination of the seed is crucial for plant development comprising of events that influence the quality of crop yield. Hence, a thorough understanding is needed in order to improve crop quality.

Seed germination involves 3 phases:

Phase 1: The first phase, imbibition occurs once the dry seed has access to water where quick hydration of the seed takes place. Most of the seeds are actually dry after their development. The water-permeable seed coats of the seed enable rapid water uptake that only slows down upon reaching the lag phase of germination (Phase II). During this phase, cellular membranes are not capable of functioning fully thus exhibiting a characteristic "leakiness" wherein compounds are detected to be leaking from the imbibing seed. This is resolved when seeds become fully hydrated. It is to be noted that some seed embryos have a perisperm envelope that prevents leakage.

Phase 2: Following imbibition is the reactivation of metabolism, a lag phase where there is a little net gain of water uptake. The seed swells, the seed coat ruptures, and the radicle comes out as a primary root. Despite the reduced water uptake, the seed is active physiologically, preparing for germination. Specifically, cellular activities involved during this phase include protein synthesis, storage reserve metabolism, mitochondrial maturation, and the production of specific enzymes.

Phase 3: The uptake of water resumes leading to radicle protrusion as the seed gains another period of weight gain and becomes established. The protrusion of the radicle is evidence that germination is taking place. Cell enlargement first occurs followed by cell division in the radicle tip. A combination of factors at play contributes to the protrusion that depends on plant species. In general, the radicle protrudes when the water potential in the radicle becomes more negative due to storage reserve metabolism. Another reason could also be the weakening of cells that allows cell expansion.   

The new embryo is entirely dependent on the food reserves produced during its development which is why germination is immediately followed by utilization of storage reserves. Carbohydrates, lipids, and proteins are the main storage reserves that are converted to sugars to fuel growth. The figure below gives an overview of the mobilization of food reserves. The embryo axis and scutellum release gibberellins into the aleurone layer. This hormone induces enzyme production followed by secretion into the endosperm. The enzymes degrade carbohydrates and proteins and convert starch into sugar. At the same time, endosperm cell wall is also digested. Finally, sugars are absobred by the scutellum and is transported into the developing embryo axis. This process provides the seed enough energy until the seed becomes photoautotrophic.]]> 2021-05-22 01:39:07 UTC https://padlet.com/zydpugasci/burdeospuga/wish/1549556439 Seed Dormancy russeljoyburdeossci https://padlet.com/zydpugasci/burdeospuga/wish/1549556716 Seeds exhibit dormancy after they are shed from the plant wherein they will not germinate even under permissive conditions. With this, germination is prevented and the condition, time, and place in which germination can occur are also regulated.

There are two types of seed dormancy observed among seeds based on the onset of the dormancy during developmental timing:

1. Primary dormancy - dormancy of newly dispersed seeds induced by ABA. Seeds do not germinate even under normal conditions.

2. Secondary dormancy - dormancy induced when the seed is in an unfavorable environment, further delaying germination usually for a long period of time. Examples of plants exhibiting this type of dormancy are Polygonum persicaria, which experiences secondary dormancy during summer, and Veronica hederofolia, dormant during winter.

All seeds exhibit both types of dormancy. In addition to the aforementioned types, dormancy can also be coat-imposed, where seedcoat and other tissues impose physiological dormancy by inducing water impermeability, mechanical constraints, inhibitory compounds, and interference in gas exchange. Meanwhile, embryo dormancy is considered innate to the seed without the influence of tissues and can be caused due to a variety of morphological or physiological factors. The hormone balance between ABA and GA is said to be the main determinant of the occurrence of seed dormancy. In the early stages of seed development, ABA is high while GA is low, favoring dormancy instead of germination. As development progresses, ABA decreases, and at the same time GA increases, this time favoring germination.

In breaking seed dormancy, several factors are at play. Light can break seed dormancy and promote germination. Herbaceous species need to be exposed to light to germinate or else they remain dormant especially when they are buried. Chemical compounds are also utilized to break dormancy mainly by decreasing ABA synthesis and increasing GA synthesis which alters the ABA: GA ratio. Stratification is another method wherein dormant seeds undergo chilling, ensuring synchronized germination and maturation. Moreover, some seeds such as Hordeum vulgare and Rumex crispus both require after-ripening to break their dormancy. During this period, seeds are stored at room temperature before they can begin germination. Machines like drying ovens are used to maintain low moisture, correct aeration, and temperature. ]]> 2021-05-22 01:39:25 UTC https://padlet.com/zydpugasci/burdeospuga/wish/1549556716 Seed Establishment russeljoyburdeossci https://padlet.com/zydpugasci/burdeospuga/wish/1549556844 Seedling establishment is defined as the stage when the seedling becomes competent enough to photosynthesize, undergo cellular and tissue differentiation, and respond to environmental stimuli without compensating for its growth and development. It was also further defined as the period between radicle emergence and exhaustion of the seed reserve, as well as the stage where the first leaf appeared.  Growth independence of the seed is crucial since they are highly susceptible to unfavorable environmental factors during this stage. However, several genes and hormones take part in this stage to promote the plant’s optimal growth.

Auxin, the master regulator of early seed development, significantly contributes to the size and shape of a mature embryo. According to Miransari and Smith (2014), the accumulation of  Indole-3-acetic acid (IAA) in the seed cotyledon is the major source of IAA for the seedlings.  Although IAA may not be necessary for the germination of seed, it is necessary for the growth of young seedlings. Auxins are produced naturally and are found in growing stems and roots where they migrate to their site of action. Other functions of Auxin in plants include: 
  • Control xylem differentiation and help in cell division
  • Stimulates growth rate
  • Control root elongation 
  • Promotes abscission
Beyond the optimum concentration, Auxin becomes inhibitory and may induce other hormones as a response. For example, is the auxin-induced production of the plant hormone ethylene inhibits root growth. Other plant hormones including abscisic acid (ABA), gibberellins, and cytokinins are biochemical substances that also contribute and control many physiological and biochemical processes in the plant. 

Seedling establishment is affected by various factors which may cause hormonal imbalance and affects the structural organization of biochemical substances in the plant. In order to counteract these adverse effects, seed priming methods have been applied to improve germination, uniformity, improve seedling establishment and stimulate vegetative growth in more field crops (Ali and Elozeiri, 2017).


]]> 2021-05-22 01:39:35 UTC https://padlet.com/zydpugasci/burdeospuga/wish/1549556844 Monocot vs Eudicot zydpugasci https://padlet.com/zydpugasci/burdeospuga/wish/1549639629 Biologists divided angiosperms or flowering plants into two groups: monocots and dicots. Monocot and dicot plants differ structurally in terms of their seeds, leaves, stems, flowers, and roots. The members of which tended to share similar features and characteristics.

 So what are the features these plants have that are similar and different? 

There are several unique characteristics a monocot and dicot plants have. Monocot or short for monocotyledon, these plants possess only one cotyledon. While dicot as hinted by its name have two cotyledons. These cotyledons are the first embryonic leaf that appears once a seed has germinated. These leaves help plants access nutrients until the true leaves are formed and ready to photosynthesize. Monocot leaves have parallel veins and long slender blades while dicots have broader leaves with branched/ reticulated veins and are connected to the stem by petioles. Many monocots do not have petioles but have a sheath that connects the blade to the stem. The monocots and dicots cross-sections can have characteristic appearances. Monocot leaves usually do not have a midrib and its blade has a more uniform thickness as compared to dicot leaf having a thick midrib and thin blade. The stems leading up to these leaves are also different; monocots have their vascular bundles scattered and most are located near the edge of the stem while dicots have their vascular bundles arranged in a ring. In addition, monocots are herbaceous plants meaning they have no persistent woody stem. When it comes to flowers, monocot flowers usually form with petals of multiples of three or termed trimerous while dicot flower petals are in multiples of 4 or 5. Beneath the soil, another important difference between monocots and dicots can be observed. Monocots have fibrous roots which splay out in different directions, sticking to the upper layer of soil. On the other hand, dicots have a taproot system which means they have one main root from which smaller roots branch off, cap roots can generally reach deeper down into the ground. Moreover, monocot roots’ pericycle gives rise to lateral roots only having a higher number of xylem and phloem arranged in oval shape while dicot roots’ pericycle gives rise to cork cambium, parts of the vascular cambium, and lateral roots with a limited number of xylem and phloem arranged in an angular or polygonal shape. Pith for monocot roots are well developed and tend to be large while dicot may be absent or very small and underdeveloped.

]]> 2021-05-22 03:21:29 UTC https://padlet.com/zydpugasci/burdeospuga/wish/1549639629 10 Endemic Plant Species in Panay Island zydpugasci https://padlet.com/zydpugasci/burdeospuga/wish/1549689892 The flora of Panay boasts of diverse native species as the island harbors a significantly vast lowland primary rainforest. Panay rainforests are home to various endemic plant species and this section shows 10 plants that are endemic on the island.

Our chosen endemic species are Begonia culiensis, Dipodium paludosum, Agatha philippinensis, Pandanus sp., Nepenthes alata, Medinilla magnifica, Paphiopedilum hennisianum, Rafflesia speciosa, Rafflesia lobata, and Shorea negrosensis. These species are restricted to mainly the mountainous regions of Panay and are vital for maintaining the ecological balance. Moreover, we hope to raise awareness that species such as Rafflesia speciosa and Rafflesia lobata are declining in numbers due to the unsustainable forest use and activities that cause its destruction (Barcelona et al. 2009). Endemic species are always at risk of being endangered or worse, extinct since their habitats are only restricted to a particular area. In addition, these lowland areas where high diversity of endemic species are thriving have always been subjected to poor conservation practices (MacKinnon, 2002). Aside from just knowing the endemic species found within the area, being aware of its current status is equally as important.
]]> 2021-05-22 04:29:55 UTC https://padlet.com/zydpugasci/burdeospuga/wish/1549689892 Tropisms russeljoyburdeossci https://padlet.com/zydpugasci/burdeospuga/wish/1550146693 Unlike animals that can move in response to environmental stimulus, we all know that plants remain sessile. That is, they need to employ other strategies that will help them cope with the challenges posed by their surroundings. How do these plants adapt to survive?

Plants grow through their environment by directional growth as a response to a directional stimulus - Tropism. There are several types of plant tropism that result in differential growth.

Phototropism - is the directional growth of the plant in response to light. This directional stimulus could either be towards (positive) or away (negative) from the light source. Light is detected by photoreceptors while the plant hormone auxin, accumulates on the shaded side causing cell elongation. Thus, the plant curves away from the auxin-filled site and towards the light.

Heliotropism - is a type of phototropism wherein the stem or flowers follow the direction of the sun as it moves. This tropism is typically observed in young sunflowers however they lose their heliotropic ability as they mature.

Gravitropism - is directional growth in response to gravity. This can be observed during seedling germination in which the emerging root grows downward following the direction of gravity (positive) while the developing shoot grows against the gravitational pull (negative). Auxin also plays a role as it accumulates on the root, causing slower growth and downward curvature.

Thigmotropism - is growth in response to touch. This is typically seen in climbing plants with tendrils. Contact with an object stimulates sensory cells on the tendril surface and tendrils coil around the object. Differential growth occurs as cells that are not in contact with the stimulus elongate faster due to high auxin concentration.

Hydrotropism - is growth in response to water concentration. In this type of tropism, abscisic acid is the key player in inducing differential growth for roots to grow in the direction of the water. This tropism protects plants from drought through positive hydrotropism and can also prevent excessive water flooding through negative hydrotropism.]]> 2021-05-22 14:50:38 UTC https://padlet.com/zydpugasci/burdeospuga/wish/1550146693 References zydpugasci https://padlet.com/zydpugasci/burdeospuga/wish/1550244163 Ali, A. S., & Elozeiri, A. A. (2017). Metabolic processes during seed germination. Advances in Seed Biology, 141-166.

Barcelona, J. F., Pelser, P. B., Balete, D. S., & Co, L. L. (2009). Taxonomy, ecology, and conservation status of Philippine Rafflesia (Rafflesiaceae). Blumea - Biodiversity, Evolution and Biogeography of Plants, 54(1), 77–93. doi:10.3767/000651909x474122

Chahtane, H., Kim, W., & Lopez-Molina, L. (2016). Primary seed dormancy: a temporally multilayered riddle waiting to be unlocked. Journal of Experimental Botany, erw377. doi:10.1093/jxb/erw377

Eurasia Review. Philippine Indigenous NGO Seed Banking For Food Security – OpEd. (2020). Retrieved from https://www.eurasiareview.com/10122020-philippine-indigenous-ngo-seed-banking-for-food-security-oped/

Gilroy, S. (2008). Plant tropisms. Current Biology, 18(7), R275–R277. doi:10.1016/j.cub.2008.02.033

Iloilo Check List. (2019). INaturalist. https://www.inaturalist.org/check_lists/14334-Iloilo-Check-List

MacKinnon, J. (2002). Preliminary analysis of the Philippine protected areas system:  gaps and recommendations. Philippine Biodiversity Conservation Priorities: A Second Iteration of the National Biodiversity Strategy and Action Plan. Pp. 58-63

Miransari, M., & Smith, D. L. (2014). Plant hormones and seed germination. Environmental and experimental botany, 99, 110-121.

Peres, S. (2016). Saving the gene pool for the future: Seed banks as archives. Studies in History and Philosophy of Science Part C: Studies in History and Philosophy of Biological and Biomedical Sciences, 55, 96–104. doi:10.1016/j.shpsc.2015.09.002

Scorza, L. C., & Dornelas, M. C. (2011). Plants on the move: towards common mechanisms governing mechanically-induced plant movements. Plant signaling & behavior, 6(12), 1979–1986. https://doi.org/10.4161/psb.6.12.18192

Taiz, L., Zeiger, E., Møller, I. M., & Murphy, A. (2015). Plant physiology and development (No. Ed. 6). Sinauer Associates Incorporated.


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