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DROUGHT AND ATMOSPHERIC VAPOR PRESSURE DEFICIT (VPD) ARE AMONGST THE MOST IMPORTANT ENVIRONMENTAL VARIABLES AFFECTING PLANT PRODUCTIVITY. VPD IS A MEASURE RELATED TO THE DRYNESS OF THE AIR; ALL ELSE BEING EQUAL, DRIER AIR WILL HAVE A HIGHER VPD. VPD IS HIGHLY SENSITIVE TO CHANGES IN TEMPERATURE AND IS EXPECTED TO INCREASE GLOBALLY DUE TO CLIMATE CHANGE. THUS, THERE IS INCREASING URGENCY TO ADDRESS AGRICULTURAL ADAPTATION TO THESE PREDICTED VPD CHANGES. STOMATA ARE MICROSCOPIC PORES ON THE SURFACES OF LEAVES BOUNDED BY A PAIR OF GUARD CELLS. GUARD CELLS ARE SPECIALIZED LEAF EPIDERMAL CELLS THAT REGULATE STOMATAL OPENING AND CLOSING IN RESPONSE TO MANY ENVIRONMENTAL CUES. THE VPD IS THE DRIVING FORCE CAUSING WATER TO EVAPORATE FROM THE LEAF. MOST PLANTS WIDEN THEIR STOMATAL APERTURE WHEN THE VPD IS LOW AND CLOSE THEIR STOMATA WHEN VPD INCREASES, TO MINIMIZE EXCESSIVE WATER LOSS. THE DEGREE AND RATE OF THE STOMATA CLOSURE VARIES BETWEEN SPECIES AND GENOTYPES. SEVERAL HYPOTHESES HAVE BEENPROPOSED TO EXPLAIN HOW STOMATA CLOSE FOLLOWING EXPOSURE TO HIGH VPD, BUT THE MOLECULAR AND PHYSIOLOGICAL MECHANISMS REMAIN POORLY UNDERSTOOD. THIS RESEARCH PROPOSES NOVEL APPROACHES TO ELUCIDATE THE MECHANISMS THAT INDUCE STOMATAL CLOSURE UNDER HIGH VPD IN THE MODEL SYSTEM ARABIDOPSIS AND THE AGRONOMICALLY CRITICAL CANOLA (BRASSICA NAPUS). USING SET OF PHYSIOLOGICAL MOLECULAR/GENETIC EXPERIMENTS, THIS RESEARCH AIMS TO IDENTIFY WHICH ENVIRONMENTAL STIMULUS IS SENSED BY GUARD CELLS (HUMIDITY, VPD, WATER LOSS), WHERE THE "SENSOR" IS LOCALIZED (EPIDERMIS, GUARD CELL WALL OR INSIDE THE GUARD CELL), AND WHETHER INCREASING VPD PROMOTES ACTIVE STOMATAL CLOSURE VIA MECHANISMS INVOLVING THE CELL WALL AND/OR PREVIOUSLY IMPLICATED INTRACELLULAR SIGNALING COMPONENTS. THE DEVELOPMENT OF CANOLA GENOTYPES WITH ENHANCED GUARD CELLS SENSITIVITY TO HIGH VPD WOULD BE HIGHLY DESIRABLE FOR WATER USE EFFICIENCY IMPROVEMENT IN FUTURE AGRICULTURE, ALLOWING REDUCED USE OF IRRIGATION. THIS RESEARCH WILL ALLOW TO IDENTIFY CANDIDATE GENES/MUTANTS TO ENGINEER OR BREED FOR CULTIVARS THAT EFFECTIVELY OPTIMIZE PHOTOSYNTHESIS AND MINIMIZE WATER LOSS BY CLOSING THEIR STOMATA WHEN VPD IS HIGH.

$57,262FY2021National Institute of Food and AgricultureUSDA

The Pennsylvania State University

Investigators

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DROUGHT AND ATMOSPHERIC VAPOR PRESSURE DEFICIT (VPD) ARE AMONGST THE MOST IMPORTANT ENVIRONMENTAL VARIABLES AFFECTING PLANT PRODUCTIVITY. VPD IS A MEASURE RELATED TO THE DRYNESS OF THE AIR; ALL ELSE BEING EQUAL, DRIER AIR WILL HAVE A HIGHER VPD. VPD IS HIGHLY SENSITIVE TO CHANGES IN TEMPERATURE AND IS EXPECTED TO INCREASE GLOBALLY DUE TO CLIMATE CHANGE. THUS, THERE IS INCREASING URGENCY TO ADDRESS AGRICULTURAL ADAPTATION TO THESE PREDICTED VPD CHANGES. STOMATA ARE MICROSCOPIC PORES ON THE SURFACES OF LEAVES BOUNDED BY A PAIR OF GUARD CELLS. GUARD CELLS ARE SPECIALIZED LEAF EPIDERMAL CELLS THAT REGULATE STOMATAL OPENING AND CLOSING IN RESPONSE TO MANY ENVIRONMENTAL CUES. THE VPD IS THE DRIVING FORCE CAUSING WATER TO EVAPORATE FROM THE LEAF. MOST PLANTS WIDEN THEIR STOMATAL APERTURE WHEN THE VPD IS LOW AND CLOSE THEIR STOMATA WHEN VPD INCREASES, TO MINIMIZE EXCESSIVE WATER LOSS. THE DEGREE AND RATE OF THE STOMATA CLOSURE VARIES BETWEEN SPECIES AND GENOTYPES. SEVERAL HYPOTHESES HAVE BEENPROPOSED TO EXPLAIN HOW STOMATA CLOSE FOLLOWING EXPOSURE TO HIGH VPD, BUT THE MOLECULAR AND PHYSIOLOGICAL MECHANISMS REMAIN POORLY UNDERSTOOD. THIS RESEARCH PROPOSES NOVEL APPROACHES TO ELUCIDATE THE MECHANISMS THAT INDUCE STOMATAL CLOSURE UNDER HIGH VPD IN THE MODEL SYSTEM ARABIDOPSIS AND THE AGRONOMICALLY CRITICAL CANOLA (BRASSICA NAPUS). USING SET OF PHYSIOLOGICAL MOLECULAR/GENETIC EXPERIMENTS, THIS RESEARCH AIMS TO IDENTIFY WHICH ENVIRONMENTAL STIMULUS IS SENSED BY GUARD CELLS (HUMIDITY, VPD, WATER LOSS), WHERE THE "SENSOR" IS LOCALIZED (EPIDERMIS, GUARD CELL WALL OR INSIDE THE GUARD CELL), AND WHETHER INCREASING VPD PROMOTES ACTIVE STOMATAL CLOSURE VIA MECHANISMS INVOLVING THE CELL WALL AND/OR PREVIOUSLY IMPLICATED INTRACELLULAR SIGNALING COMPONENTS. THE DEVELOPMENT OF CANOLA GENOTYPES WITH ENHANCED GUARD CELLS SENSITIVITY TO HIGH VPD WOULD BE HIGHLY DESIRABLE FOR WATER USE EFFICIENCY IMPROVEMENT IN FUTURE AGRICULTURE, ALLOWING REDUCED USE OF IRRIGATION. THIS RESEARCH WILL ALLOW TO IDENTIFY CANDIDATE GENES/MUTANTS TO ENGINEER OR BREED FOR CULTIVARS THAT EFFECTIVELY OPTIMIZE PHOTOSYNTHESIS AND MINIMIZE WATER LOSS BY CLOSING THEIR STOMATA WHEN VPD IS HIGH. · GrantIndex