Location: National Peanut Research Laboratory
Project Number: 6044-21000-006-006-R
Project Type: Reimbursable Cooperative Agreement
Start Date: May 1, 2023
End Date: Apr 30, 2027
Objective:
OBJECTIVE 1. Discover underlying physiological mechanisms of water spender and water saver cultivars. We will evaluate 4 peanut lines with different drought tolerant traits and 1 susceptible line. In our previous study, two peanut lines (Line-8 and AU-16-28) were identified as 'water savers' which can shutdown physiological response to minimize water loss and peanut lines (PI 502120 and AU-NPL 17) are 'water spenders' which keeps growing under a short term drought stress. Peanut will be grown in AL and GA under drought and control treatments and physiological traits will be measured, such as high water use efficiency, effective use of water, nitrogen fixation and root characteristics using semi and high-throughput phenotyping techniques. RNA sequencing will be performed to correlate gene expression with physiological traits to identify molecular and genetic controls.
Approach:
Physiological measurements will be taken of 5 peanut cultivars in two rain-out shelter locations in Alabama and Georgia, to be combined with modeling to identify the ideal locations to maximize long term yield under different climate change scenarios using this drought tolerant strategies in the peanut belt. Second, a bi-parental population created from the cross of a water saver and a water spender drought tolerant peanuts will be genotyped by next generation sequencing (NGS) and phenotyped to find the QTLs related with these two drought tolerant strategies. RNA-sequencing from the detailed physiological experiment and from the extremes in the bi-parental population experiments will help to hypothesize which genes may be involved in the control of these two drought tolerant mechanisms. Details of experiments: Two previously selected water saver (Line-8 and AU-16-28) and two water spender (PI502120 and AU-NPL 17) drought tolerant cultivars, along with one drought sensitive cultivar (AP-3) used as a check will be grown under two different rainout shelter environments on the first two years of this grant (Summer 2023 and 2024). The first one is located at the USDA-ARS National Peanut Research Laboratory (NPL) in Dawson (GA) and are composed of 6 metal structures that are designed to close automatically during each rain event. Each metal shelter covers a ground area of 18 x 40 feet over a Tifton sandy loam soil. For this experiment, three shelters will be used to implement drought with each shelter counting as one replication, while the other three will be maintained under constant irrigation. The second environment is located at the Auburn University EV-Smith Research Center (AL) and is composed of 4 plastic greenhouses with automatic and retractable walls and ceiling. Each plastic shelter covers a ground area of 30 x 48 feet and consists of a loamy sand textured soil and will be used to implement drought counting as one replication per shelter. Adjacent outside plots will be placed beside the shelters as irrigated controls for a total of four replications. In both locations seeds will be planted by hand in early May with a week of separation between locations to enable staggered measurements. In Dawson, seeds will be planted to form at least three rows of 10-feet long plots per cultivar and shelter. At EV-Smith, the shelters are bigger, so 4 row plots 12-feet long will be planted inside and outside the shelters. Drought will be imposed at mid-season (~70 days after planting) for 4 weeks. Physiological measurements will be performed twice a week during drought. Leave tissues will be collected at start of drought and at 17 days after start of drought correlating with physiological responses. RNA sequencing will be performed to identified drought regulated genes. Specific gene regulations will be correlated to physiological measurements and yield to identify drought tolerant peanut lines. This information will be integrated in peanut breeding program to develop drought tolerant peanut genotypes.
