The genetics involved in the development of flowers, pollen, and nuts in protandrous and protogynous Carya illinoinensis cultivars: the half circle of life

Authors: RANDALL, JENNIFER - New Mexico State University; HARMON, ANNA - New Mexico State University; RHEIN, HORMAT SHADGOU - New Mexico State University; MARCUS, MADISON - New Mexico State University; DENA, FRANCISCO - New Mexico State University; CERVANTES, KIMBERLY - New Mexico State University; MASON, KAITLYN - New Mexico State University; ANDAZOLA, ANDRA - New Mexico State University; SONG, JOE - New Mexico State University; HEEREMA, RICHARD - New Mexico State University; Wang, Xinwang; SREEDASYAM, AVINASH - Hudsonalpha Institute For Biotechnology; LOVELL, JOHN - Hudsonalpha Institute For Biotechnology; SCHMUTZ, JEREMY - Hudsonalpha Institute For Biotechnology; GRIMWOOD, JANE - Hudsonalpha Institute For Biotechnology; JENKINS, JERRY - Hudsonalpha Institute For Biotechnology; Grauke, Larry

Submitted to: Plant and Animal Genome Conference
Publication Type: Abstract Only
Publication Acceptance Date: 1/12/2024
Publication Date: 1/17/2024
Citation: Randall, J., Harmon, A., Rhein, H., Marcus, M., Dena, F., Cervantes, K., Mason, K., Andazola, A., Song, J., Heerema, R.J., Wang, X., Sreedasyam, A., Lovell, J., Schmutz, J., Grimwood, J., Jenkins, J., Grauke, L.J. 2024. The genetics involved in the development of flowers, pollen, and nuts in protandrous and protogynous Carya illinoinensis cultivars: the half circle of life. Plant and Animal Genome Conference. San Diego,CA;12-17Jan2024.

Interpretive Summary:

Technical Abstract: Carya illinoinensis, commonly known as pecan, is native to North America and is an economically important tree species that is grown for its nutritious and delicious nutmeats that are rich in beneficial proteins, lipids, and antioxidants. Flowering and fruiting are physiologically stressful events, and in conjunction with environmental stresses there can be extreme variability in fruiting and nutmeat quality. Several studies were designed and performed to determine the genetics and key characteristics of distinct time points impacting flowering, pollen, and pecan seeds. Pecan trees are heterodichogamous with both pistillate and staminate flowers produced on the same tree. RNA-Seq studies were performed on protogynous and protandrous cultivars to elucidate the genetic signals associated with flowering. The RNA-Seq results revealed specific genetic signals responsible for catkin production. As pecan trees are not prone to self-pollination it was important to determine the amount of time and the germ tube length of pollen from protogynous and protandrous pecan cultivars. In-vitro pollen studies were performed with the protogynous cultivars having the shortest germination times (as little as 12 minutes) and protandrous cultivars having the longest germination time with 'Osage' having 57 minutes. Gene expression analyses showed that 'Lakota' germinated pollen expressed higher levels of CiRac-like gene during germination than 'Pawnee'. There was a significant difference observed in gene expression of in-vitro germinated pollen 'Pawnee' and 'Lakota' in the CiRac-like gene that is required for pollen development. This data indicates that differences in overall gene expressions control pollen development for protogynous and protandrous cultivars. The pollens used in the in-vitro study were also used in performing controlled crosses with protandrous and protogynous cultivars. Pistillate flowers that were 'self-pollinated' with the pollen from the same tree produced the least number of nuts and the nuts were not as large as the nuts that developed from other pistillate flowers/pollen combinations. The 'Wichita' x 'Pawnee', and the 'Wichita' x 'Western' crosses produced the most nuts per cluster with the controlled crosses. The 'Wichita' x 'Western' cross had the average highest mass per nut. In addition, gene expression studies are in progress to elucidate the genes that control seed germination. These genetic data are important to understand the impacts of development and climate on the production of pecan nuts in the United States.