Phyllotaxy

This is usually are of four types – alternate, opposite, spiral and whorled

In alternate type of phyllotaxy, a single leaf arises at each node in alternate manner, as in china rose, mustard and sunflower plants

Phyllotaxy

In opposite type, a pair of leaves arise at each node and lie opposite to each other as in Calotropis and guava plants.

If more than two leaves arise at a node and form a whorl, it is called whorled, as in Alstonia (Devil Tree) Apocynaceae

Spiral phyllotaxy

Fibonacci sequence

Golden Angle

the divergence angle between successively arising leaves is fixed at the golden angle of 137.5°

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P. syringae pv. Syringae (Pss) secrete syringolin A (SylA), a peptide derivative synthesized by a mixed nonribosomal peptide synthetase/polyketide synthetase encoded by a gene cluster. 

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The effector SylA is secreted by the bacteria into the host plant cells. Once inside the cells, SylA irreversibly inhibits the proteasome

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Fusicoccum amygdali produces the toxin fusicoccin, which targets the plasma membrane H+‐ATPase in many plant species

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Sclerotinia sclerotiorum is a necrotrophic fungus that infects over 400 plant species. It secretes the phytotoxin oxalic acid to assist the early phases of the infection

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Phytopathogenic bacteria reside within the intercellular spaces of plant organs or in the xylem and many damage plant tissues by secreting toxins, extracellular polysaccharides (EPSs), or cell wall‐degrading enzymes.

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Coronatine is a toxin effector produced by the bacterium Pseudomonas syringae to mimic the plant hormone jasmonic acid‐isoleucine and this assists bacterial infection.