Pollen tube are tolerant and even pollen damaged by X-rays and gamma rays can still grow pollen tubes. The interaction between the stigma-style and the pollen grain is a vital piece that contributes to the growth. The elongation of the tube is achieved with elongation of the cytoskeleton and it extends from the tip, which is regulated by high levels of calcium in the cytosol. The calcium levels help the synaptic vesicles in the membranes grow and extend at the tip. Polypeptides found in the style also regulate growth of tube and specific peptides that play a role in signaling for growth
Husk Husk Husk (or hull) in botany is the outer shell or coating of a seed. It often refers to the leafy outer covering of an ear of maize (corn) as it grows on the plant. Literally, a husk or hull includes the protective outer covering of a seed, fruit, or vegetable. It can also refer to the exuvia of bugs or small animals left behind after moulting. In cooking, hull can also refer to other waste parts of fruits and vegetables, notably the cap or sepal of a strawberry. The husk of a legume and some similar fruits is called