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  • From: "Lawrence F. London, Jr." <lfl@intrex.net>
  • To: livingontheland@lists.ibiblio.org, tawapanm@mm2k.net
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  • Subject: [Livingontheland] [permaculture] Plastic vs. Plants: Mulch method changes tomato's gene activity: Science News Online, July 10, 2004
  • Date: Wed, 14 Jul 2004 10:40:42 -0700

"Lawrence F. London, Jr." <lfl@intrex.net>

<http://www.sciencenews.org/articles/20040710/fob5.asp>
Week of July 10, 2004; Vol. 166, No. 2 , p. 21
Plastic vs. Plants: Mulch method changes tomato's gene activity

Susan Milius

A suite of at least 10 genes in a tomato plant behaves differently depending
on the farmer's mulch-and-fertilizer routine, according to an
unusual analysis.

MULCH MATTERS. Two fields of Sunbeam tomatoes planted at the same time and
photographed on the same day. In a season with adequate rainfall,
tomatoes mulched with black plastic and given standard fertilizer (above)
developed more leaf diseases and aged faster than the same variety
planted in mown vetch and given half the fertilizer (below).
Dave Clark

Earlier work showed that when researchers mulch with a layer of mown vetch
instead of the conventional black plastic, tomato plants live
longer and develop less fungal disease, says Autar Mattoo of a Department of
Agriculture laboratory in Beltsville, Md. He and his colleagues
now report insight into the underlying plant chemistry.

Among the genes that kick into higher activity in vetch-mulched fields are
two for plant defense and two for regulation of aging, the
researchers say in an upcoming Proceedings of the National Academy of
Sciences. "This kind of molecular analysis had not been done before,"
says Mattoo.


Dave Clark

The vetch system has been around for decades among farmers practicing
environment-friendly agriculture. Over the winter, the farmers grow
hairy vetch, a member of the bean family, and they mow it in the spring. They
then set out tomato plants in the matted vetch, which
discourages weeds and boosts nutrients in the soil.

Beltsville researchers compared vetch-mulched fields given half the normal
dose of commercial fertilizer with plastic-mulched fields given a
full dose of fertilizer. In years with sufficient rainfall, the vetch-treated
fields yielded a Sunbeam tomato crop bigger than that of
fields receiving conventional treatment. Although the plastic mulch provided
the crop a little sooner, the vetch mulch offered other
benefits, including reduced erosion, decreased signs of fungal disease on
leaves, and delays in plant aging. These benefits appeared during
two seasons but not in a third, when there was a severe drought.

To search for a mechanism behind the disease and aging benefits, Mattoo,
Vinod Kumar of the same lab in Beltsville, and their colleagues
studied proteins and genes in tomato plants grown in the two
mulch-and-fertilizer systems. Among their analyses, the researchers used a
technique that highlights differences in gene activity.

Among the genes that kicked into higher activity in vetch-mulched plants are
a gene for chitinase, an enzyme that chews up the cell walls of
attacking fungi, and a gene for osmotin, another defensive compound. The
researchers also found extra activity for receptors for cytokinins.
These plant hormones, which travel from the roots to the rest of the plant,
are regulators of aging.

Mattoo has many ideas to explain the difference in the effects of the two
crop-growing methods. For instance, he points out that nutrients
can influence gene activity and that vetch-mulched tomatoes typically produce
especially robust root systems that take up soil nutrients
efficiently.

Plant physiologist Thomas Sinclair of the USDA in Gainesville cautions that
the patterns of gene activity reported so far are "correlations,
not cause and effect." He adds that whatever the physiology turns out to be,
"I'll guarantee you it's going to be very complicated."

If you have a comment on this article that you would like considered for
publication in Science News, send it to editors@sciencenews.org.
Please include your name and location.

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  • [Livingontheland] [permaculture] Plastic vs. Plants: Mulch method changes tomato's gene activity: Science News Online, July 10, 2004, Lawrence F. London, Jr., 07/14/2004

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