• University of California, Davis

• PLB 112

 1. What are the male and female gametophytes of a flowering plant called? How many cells do they each have? 2. Briefly explain why double fertilization in a diploid plant results in a diploid embryo but a triploid endosperm. 3. What is the ratio of maternal to paternal genomes in the following examples: a. Endosperm of seed from self-pollination of a diploid (2N) plant b. Embryo of seed from a pistil of a hexaploid (6N) plant crossed with pollen from a diploid (2N) c. Endosperm of seed from a pistil of a diploid (2N) crossed with pollen from a hexaploid (6N) d. Which of the crosses above (a, b, c) will produce the largest seeds, and which one will produce the smallest seeds? Explain briefly. Flower Development 1. What are the floral phenotypes of the following plants: a. ap2 ap3 double mutant b. 35S:AG transgenic plant c. 35S:AP3 35:PI in an ag mutant transgenic plant d. pAP1::miR172 transgenic plant 2. Propose a mutant or combinations of mutants that will have the following phenotypes: a. carpels, stamens, stamens, carpels b. (sepals, sepals, sepals, sepals) repeating c. sepals, petals, stamens, stamens 3. Propose a set of transgenes that will convert leaves to carpels. 4. Briefly describe the interactions between the LFY, WUS and AG genes that ensures that the floral meristem will terminate after making the carpels. Transition to Flowering 5. Photoperiod and Flowering a. Outline the interactions between CO, FT and LFY that lead to flowering in the presence and absence of the proper photoperiod in an LD plant. b. Why does expression of CO mRNA in the dark fail to produce much CO protein? c. You are interested only in photoperiod and flowering. You screen for Arabidopsis mutants that flower early under Short Day conditions. You find two mutants that flower early, early flowering1 (ef1), and early flowering2, (ef2). (This is a hypothetical example). You investigate these mutants further, and find the following properties: i. ef1 is epistatic to ef2 ii. ef2 ft double mutant - flowers early iii. ef1 co double mutant - flowers late